Method of making metal packing-rings.



M. L. WILOOX. METHOD OF MAKING METAL PACKING RINGS.

APPLICATION FILED APR. 15, 1913.

1,1 16,776. Patented Nov. 10, 1914.

llllllml .WITNEISSES: IIIYENTIOR I I ATTORNEY I engine cylinder. A

either eccentrically or axially, as the case MELVIN L.- wILcox, orFLINT, MICHIGAN.

METHOD OF MAKING METAL PACKING-RINGS.

Specification of Letters iatent.

Patented Nov. 10, 1914.

Application filed April 15, L913. Serial No. 761,223.

To all whom it may concern Be it known that I, MELVIN L. ILCOX, acitizen of the United States, reslding at Flint, in the county ofGenese-e and State of Michigan, have invented certain new and\ usefulImprovements in Methods of Making Metal Packing-Rings; and I do herebydeclare the following to. be a full, clear, and exact description of theinvention, such as will enable others skilled in the art to which itappertains to make and use the same.

This invention is a method of making metal packing rings for use inengines and similar machines and is especially adapted for the making.of piston rings for internal combustion engines. In this class ofengines' it is of importance that the piston rings shall fit thecylinder accurately and that all points around the periphery of the ringshall exert equal outward. pressure against the cylinder. To producethis resuit, rings, to the making of which my improved method applies,are commonlymade of cast metal and turned on the outside to a diameterslightly larger than the bore of the The ring is then bored may-be, thebore being slightly larger in diameter than the bottom of the pistongroove in which the ring is to be used. A ring is thus produced,assuming it to have been bored eccentrically, that is thinnest at theextremity of one diameter and thickest at the other extremity of thesame diameter. Such a ring, when split'at the thinnest part will, if ofuniform density and elasticity throughout its periphery, tend to exert apressure against the cylinder wall approximately equal at all pointsaround the circumference, when sprung into place. It has been found inpractice, however, that such rings if made of ordinaryiron are seldom ofuniform density andQelasticity, and if made of. alloy thatimparts'as'uflicient ela s ticity to produce the desired resilience,the" ring is likely to be so hard as to damage the cylinder. i

Various methods have been devised for producing split piston of variablethickness, to irnpart-rthel'desired' degree of elasticity, but usuallysuchime'thods are very expensive, because'of the fact that the rings aremade one at a time. c

- My improved method provides for the making of a number of rings at oneoperation and insures a uniformdegree of elasticity and consequent evenpressure against the cylinder well clear around the periphery. My methodalso corrects any defects such as soft spots in the metal of the ring,thereby saving for use many rings that would otherwise have to be thrownout. My method further enables rings to be made of gray iron or ironcontaining only a small percentage of alloy, and yet to be of smallercross-section than would otherwise be per missible. The advantages ofsmaller cross- .section of piston rings for explosive engines are,first, less rubbing area against the cylinder Wall, second, less outwardpressure of the ring against the cylinder wall at the instant ofexplosion, because of less area exposed to the gases at the back orinner bore ofthe ring. v

My improved method consists in the steps set forthand claimed and theequivalents thereof.

The' accompanying drawings illustrate diagrammatically the devices andsteps emplofyed. V

Figure 1 is a plan View of a split ring of the kind to which my methodis applicable;

,Fig. 2 is a side view of the same; Fig. 3 i a longitudinal section of apot or shell or shell 1 open at both ends and of length.

suflicient to yield any convenient number of piston rings, say six ormore. Second, to shape by turning, grinding, or otherwise, the outsidesurface 20 of the shell, to cylindrical form-the outside diameter beingpreferably slightly larger than the bore of the engine cylinder in whichthe ring is to be ,used. Third, to bore the interior 3 of the shell, thebore being slightly eccentric so as to make the wall of the shellthinner on one side as at lfl Fourth, to mount the shell in acylindrical container 5 that fits and supports the outside wall of theshell. Fifth, to direct against the interior surface of theshell, astream 6 of projectiles, as for instance, small steel balls propelled byan air blast, the stream being directed so as to successively impingeagainst the shell surfaces until the entire interior area of, the shellhas been uniformly treated throughout. It is not essential that steelballs be used, or that air-.be the prb elling medium, but anysuitablegas may 'e used instead and any kind of projectile thatis-capable of producing a swaging or hammering. action like. that of .5hardsteel. balls-may be used Sixth, to sever s the swaged' shell toproduce a pluralit of piston rings (shown in Fig. 2). Sevent to spliteach ring in the ordinary way as at 7. Eighth, to draw together thesplitnds of the ring and grind or otherwise finish the compressed ringto the proper size for the cylinder. By this method of firstproducing aneccentrically bored shell comprising a number of rings and then swagingthe en- 15, tire inner surface of the shell by means of a blast of steelballs or their equivalent, almost perfectly uniform results as totension are produced, and in a small fraction of the time that would berequired to swage go each ring separately. Since the shell is thinner onone side, no care need be exercised to vary the intensity of the blowsof the proj ectiles, thereby further increasing the speed of operation.Handling is reduced to a 5 minimum, and the cost of production is cut toa very small fraction of the cost of producing similarly shaped rinsgsone at a time. The intensity of the swaging action is easily controlledby varying the force of the air blast, although once set, it requiresvery little regulating. Another advantage of this method is that theoutward pressure exerted by the ring against the cylinder wall ispractically uniform and the pressure is about twenty per cent. in excessof that of the :ordinary ring of the same design that has not beenswaged as above described. Conse quently rings made by my method may betwentyper cent. narrower and will exert I 40 correspondingly smallerpressure against the ....:cylinder wall at the moment of explosion. Aconsiderable saving of material is also eifected by this permissiblereduction in width of the ring.

While- I have described the fifth step of :the method as constitutingthe swaging and the sixth step as the severing of the shell into aplurality of rings, it would be within the scope of my invention totranspose these s'tepsthat is, to first sever the rings and then topilethem into the container and'diroot the swage blast against them. Iprefer, however, to use in practice the steps as first I enumerated. o

-While I have described my improved method as applied to the treatmentofeccentrically bored rings that are thinnest at the end of one diameterand thickest at the opposite end of the same diameter, it will beunderstood that the described method of treating the interior surface ofthe shell, viz.

and finishing the exterior peripheries of the rings, which comprisesassembling the rings rings by forcing their severed ends together,

J Having' described my invention, what I claim and desire to secure byLetters Patent:

1. The method of tensioning packing rings, which comprises assemblingthe rings end-to-end to form a pot, and directing a stream of looseprojectiles against the entire interior of the pot to swage the surfaceof the bore.

2. The method'of making metal packing rings, which consists in producinga pot or shell of sufficient length to comprise a plurality of rings,turning the exterior of said shell to cylindrical form, veccentricallyboring the interior of. the shell, severing the shell to produce aplurality of rings, assembling the-rings end-to end, directing a streamof gas-propelled projectiles against'80 the entire interior of theassembled rings, to swage the surface of the bore, splitting the rings,temporarily closing the rings by forcing their severed ends together,and finishing the exterior peripheries of the closed rings, whichcomprises, producing a pot or rings are to be used. a

3. The method of making metal packing rings, which comprises, producinga pot or shell of sufficient length to include a plurality of rings,turning the exterior of said shell to cylindrical form, eccentricallyboring the interior of the shell, severing the shell to produce aplurality of rings, assembling the rings end-to-end, directing a streamof air-propelled hard metal balls against the entire interior of theassembled rings to swage the surface of the bore, splitting the rings,temporarily closing, the rings by forcing their severed ends together,

closed rings to the size of the cylinder in which the rings are to beused. s

l. The method of tensioning packing end-to-end to form a pot, directinga stream a of projectiles against the entire interior of the pot toswage the surface of the bore,

splitting the rings, temporarily closing-the and finishing the exteriorperipheries of the closed ringsto the size of the cylinder in which therings are to be used. 5. The method of tensioning packing rings, whichcomprises assemblingthe rings end-to-end to form a pot, directing astream 1 of loose projectiles against the entire interior of the pot toswage the surface of the bore, and splitting the rings.

In testimony whereof, I affix my signature in presence of two witnesses.

MELVIN L. wiLoox.

lVitnesses:

NELLIn M. ANGUs, JOSEPH V. CARPENTER.

